There are many instances as well known, particularly under boundary lubrication conditions, where two rubbing surfaces must be lubricated, or otherwise protected, so as to prevent wear and to insure continued movement. Moreover, where, as in most cases, friction between the two surfaces will increase the power required to effect movement and where the movement is an integral part of an energy conversion system, it is most desirable to effect the lubrication in a manner which will minimize this friction. As is also well know, both wear and friction can be reduced, with various degrees of success, through the addition of a suitable, or combination thereof, to a natural or synthetic lubricant. Similarly, continued movement can be insured, again with varying degrees of success, through the addition of friction modifier.
Numerous means have been employed to reduce the friction in internal combustion engines. These range from the use of lower viscosity lubricating oils, or mixtures of mineral and synthetic lubricating oils, as well as to the incorporation of friction-reducing additives such as graphite, molybdenum compounds and other chemical additives. There are limits to the extent to which the viscosity of a lubricating oil can be reduced for the purpose of reducing friction. Generally, a lubricating oil, havng too light a viscosity, will fail to prevent metal-to-metal contact during high-load operating conditions with the result that unacceptable wear will occur in the engine. With respect to chemical anti-friction additives, significant research efforts are going to find effective and economic anti-friction additives which exhibit stability over an extended service life and under a wide range of operating conditions.
It is an object of this invention to provide a novel lubricating oil composition for a gasoline crankcase engine.
It is another object of this invention to provide an overbased lubricating oil having improved friction properties for lubricating gasoline crankcase engines.